Improvement in steam-engines



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` JOHN H. MCGOWAN AND DAVIDB. CALDWELL, OF CINCINNATI, OHIO.

IMPROVEMENT -IN STEAM-ENGINES.

Specification forming part of Letters Patent No. 119,039, dated September 19, 1871.

liability of a reciprocating steam-engine to stick or become detained at the dead-points.

When a reciprocating engine of the customary construction comes to rest, as it often will, at one or other extremity of its stroke, it is well known to be practically immovable by any force of steam actingupon the piston, and consequently in the line of the stroke, although a comparatively slight force perpendicular to the said line is competent to start the crank-wrist on its proper rotation to a point Vin the circle at which the force of the steam acting throughthe piston-rod and pitman becomes available.

The present invention is a mechanical contrivance, `entirely automatic in its action, whereby a small portion of the steam power at the effective parts of the stroke, being stored up, is returned to the engine at the extremity of the stroke and becomes eifectivethe moment that the steam is let into the valve-chest to carry the crank-wrist past the dead point.

Figure 1 is a partially-sectionized elevation of an engine provided with our improvement, the main crank-wrist being at the extremity' of its outward stroke, and consequently at dead-point, and our auxiliary wrist and pitman being at halfstroke, and consequently at their most effective starting position. Fig. 2 is a section at right angles to Fig. 1,V representing the auxiliary piston at the end of its stroke. Fig. 3 is a diagram showing the main crank-wrist at the inner dead point, the auxiliary wrist, having made an entire revolution, being again'v at i its half-stroke and effective position.

A, B, C, and D may represent a steam-cylinder, piston-rod, pitman, and crank-wrist of customary construction. The main crank-shaft has a spurwlieel, E, that gears with a pinion, F, of precisely half the diameter of said wheel, and consequently making two rotations to one of the main crankshaft.` G is anauxiliary cylinder of 4'comparatively small diameter, preferably closed at bottom, where it communicates freely `by pipe K with the steam or valve-chest L, and packed at its open end to receive a plunger, H, whose pitman, I, is connected to awrist, J, so located upon the pinion F as to be always at the most eifective position of its stroke at the dead-points of the main engine.

While describing the preferred form of our invention we reserve the right to vary the details of construction-for example, the auxiliary cylinder may connect with the steam-pipe at some point between the throttle and the valve-chest, and the entire auxiliary arrangement may be made capable of being readily ungeared from the engine proper at the option of the engineer. The auxiliary cylinder may be an oscillatin g one, whose rod, passing through a stuffing-box in the front head, may communicate directly with 'its wrist without the intervention of a pitman. The auxiliary Wrist may be adjustable toward or from the center of the pinion, according to the pressure of steam employed, a lighter pressure requiring a greater radial distance or leverage of the wrist to overcome the friction of the main engine, while with a high pressure such leverage would be superiiuous, because directing an unnecessary expenditure of power that would cause the main engine to labor at half stroke.

The enginerhaving lodged at one of its deadpoints, as in Fig. l, let the throttle be opened. It is apparent that the pressure of the steam against the main piston being radial to and directly in the plane of the crank-shaft cannot possibly move the crank, but a very slight forceV applied tangentially to said shaft will be adequate to start its revolution to a point at which the main pitman can become eective, and this force is 'afforded by the steam in the small auxiliary cylinder G, which, elevating the plunger H, operates through the auxiliary pitman I and wrist J to rotate the pinion F and wheel E, and thusV to start the main crank-shaft'on its rotation. This very essential desideratum is attained with absolutely no expenditure of power other than the slight condensation and friction of the auxiliary engine, all the force appropriated by the auxiliary cylinder being given back to the engine proper without loss.

I claim- The within-described arrangement of auxiliary cylinder Gr, plunger H, pitman I, wrist J, and spur and pinion E F, substantially as and for the purpose set forth.

In testimony of which invention we hereunto l i witnesses; DAviD B. CALDWELL.

GEO. H. KNIGHT, JAM-Es H. LAYMAN. 

